<html>
<head>
<title>Formulier verzenden</title>
<style>

</style>
<script src="//ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
</head>
<body>

<form id="frm1" method="post" action="formsessie.php">

<label>Straat: </label>
<input type="text" name="straat" value=""><br>
<label>Postcode: </label>
<input type="text" name="postcode" value="">
<p>
<input class="r1" type="radio" name="actie" value="1">Verzend met if statement<br>
<input class="r1" type="radio" name="actie" value="2">Verzend met sessie en location<br>

<input type="submit" name="submit" value="verzend met sessie">

</p>
</form>

</body>
<script>

$(document).ready( function() {

	$('.r1').on('change', function() {
			if ($(this).val() == 1)
				$('#frm1').attr('action','formulier.php');
			else
				$('#frm1').attr('action','formsessie.php');

	});

});
</script>
</html>